The Role of Vision in Single-Leg Balance

Abstract

It is something that we all take for granted, but humans’ ability to balance is a complex task. Upright stance is not a stable equilibrium, and without any control from our muscles, even the smallest disturbances would cause us to fall over. In this study, I looked into how the integration of different sensory feedback mechanisms allows us to properly balance when performing tasks such as walking, jumping, or standing on one foot. Specifically, I wanted to examine the role of vision in balance, and strategies we deploy to balance without it. When we close our eyes, how does our body make up for this loss of information, if at all? In order to better understand this question, we had participants stand on one leg with their eyes open and closed, and their preferred balancing strategies for each trial were tracked. It was observed that when subjects had their eyes open, they preferred to use the ankle strategy, in which one actuates their ankle in order change their center of pressure. Without vision, the subjects incorporated the hip strategy in concert with the ankle strategy, oscillating their torso side to side in order to stabilize their center of mass. I then compared this experimental data to an inverted pendulum model in order to see if I could isolate the role of vision from other feedback, and saw that a strategy analogous to our subjects’ hip strategy was employed once the model was unable to determine its absolute height. These findings are a first step to help us understand exactly how the sensory information we receive is reflected in our behavior, and points us towards interesting questions in human sensory integration which can help better inform sensory processing disorders.